Is Unnerving Assault legal in Standard, Modern, and Commander?

Unnerving Assault is legal in: Modern, Legacy, Vintage, Commander.

Unnerving Assault

Q: What type of card is Unnerving Assault?

Unnerving Assault is an Instant. Its oracle text reads: "Creatures your opponents control get -1/-0 until end of turn if {U} was spent to cast this spell, and creatures you control get +1/+0 until end of turn if {R} was spent to cast this spell. (Do both if {U}{R} was spent.) *The scales of battle rarely balance.*"

Instant

Creatures your opponents control get -1/-0 until end of turn if was spent to cast this spell, and creatures you control get +1/+0 until end of turn if was spent to cast this spell. (Do both if was spent.)